Fix: When using 'AFTER_JS' hook, try to insert it in the head, and not with inline javascript in the body.
Added a (short) style rule for 'bolt_widget'.
Change: removed the entire 'app/extensions/' path from Twig by default.

From now on, it's the extensions responsibility to add a path, if its'
needed:

    $this->app['twig.loader.filesystem']->addPath(__DIR__);
Don't sort taxo's when there's nothing to sort. Fixes #224.